How model the fact table

I'm building a DW but I'm not able to design a fact table that show what i need. My design until now is that :

Table: dimPatient

ID_PACIENT	NAME	AGE
1	AAA	18
2	BBB	21

Table: dimSirurgy

ID_SIRURGY	ID_PACIENTE	date_fact	date_pay	COST	nm_description	nm_doctor
100	1	2013-01-01	2013-06-01	10000	DESC 1	DOCTOR 1
200	2	2013-05-01	2013-06-01	15000	DESC 2	DOCTOR 2

Table: dimExam

ID_EXAM	id_patient	date_fact	nm_description	HOSPITAL
05	1	2013-02-01	DESC 1	HOSP A
10	1	2013-02-01	DESC 2	HOSP A
15	2	2013-05-01	DESC 3	HOSP B
20	2	2013-05-01	DESC 4	HOSP B

Table: dimDate

ID_DATE	DATE
1	2013-01-01
2	2013-02-01
3	2013-03-01
4	2013-04-01
5	2013-05-01
6	2013-06-01
7	2013-07-01

Table: Fact

ID_PACIENT	ID_SIRURGY	ID_EXAM	ID_DATE	SUM COST
1	100	NULL	1	10000
1	NULL	5	2	NULL
1	NULL	10	2	NULL
2	200	15	5	150000
2	200	20	5	150000

If you see the rows in the fact table are duplicate. For example I wanna know the cost of the sirurgy but the cube was return the sum of the duplicate rows, probably because its model in the wrong way.

The rule for these tables are that one patient could make only one sirurgy per day, but could do more than one exam in a day.

Thanks in advance

Normally this is modeled at the procedure grain. One row per patient/procedure/date. The costs are recorded as known for that procedure, not a combination of all procedures for a given encounter. Capitated procedures, such as exams could be booked at a standard cost. Recorded as null in your example is another possible method, but can be misleading in clinical analysis and actuarial studies.

Thank you for your reply ngalemmo.

Just let me see if I understand what you said. My fact table should be like that :

Table: Fact

ID_PACIENT	ID_SIRURGY	ID_EXAM	ID_DATE	SUM COST
1	100	NULL	2	10000
1	NULL	5	1	NULL
1	NULL	10	1	NULL
2	200	NULL	5	150000
2	NULL	15	5	NULL
2	NULL	20	5	NULL

One row per procedure, indepedent if its in the same day ?

Thanks

One FK as well, Procedure ID. The procedure dimension would include all procedures (exams, surgeries, dispensing medications, etc...). Procedures are usually identified using CPT or ICD coding systems (or whatever standard coding system in your region).

The dimension would only contain information about the procedure... not the patient or location or booking dates. Those are dimensions that should be referenced from the fact.